1. Field of the Invention
The present invention relate to a base material for a honeycomb core structure having an excellent resistance to corrosion, water and moisture, and which is light weight.
More particularly, the present invention relates to a base material having not only an excellent resistance to corrosion, water and moisture, but also a superior mechanical strength, heat resistance, and property preventing a strike-through phenomenon of a resin material, for example, an adhesive, and having a light weight and being useful for various types of honeycomb core structures in portions of aircraft, parts of cars, construction and building materials, parts of ships, parts of drawing boards, parts of skis, air flow-regulating boards of open showcases, air flow-regulating boards of spinning chimneys, louver materials of illumination units, and shock absorber materials of pressing machines.
2. Description of the Related Arts
Conventional honeycomb core structures have been made from base materials consisting of aluminum foil or kraft paper. For example, a honeycomb core structures made from an aluminum foil has a high mechanical strength and has been used for a part of an aircraft. However, for such a part of an aircraft, it has been required that the weight should be significantly reduced and the reliability in mechanical strength should be enhanced. Therefore, development of a honeycomb core structure having a further reduced weight and a further enhanced mechanical strength has been desired.
Also, various types of honeycomb core structures made from a base material consisting of kraft paper have been generally used for various purposes. However, the kraft paper honeycomb core structures are disadvantageous in that they have an unsatisfactory mechanical strength, a large change in dimension in wet conditions, and a low resistance to corrosion, though the weight is satisfactorily light.
As a base material for a honeycomb core structure having a light weight and a high thermalstability, a paper-like sheet made from aromatic polyamide fibers and pulp particles (Trademark: Nomex Paper, made by Du Pont) is known. The paper-like sheet is produced from a mixture of poly-m-phenylene isophthalamide staple fibers and pulp particles by means of a wet paper-making procedure. Since, however, the paperlike aromatic polyamide sheet is expensive, this type of honeycomb core structure is now utilized only for special purposes, for example, for aircraft parts, and has not yet been applied in a broad scope of industry.